A method and apparatus for controlling the steering of an automatic guided vehicle (AGV) includes simultaneously correcting the vehicle's heading and position errors. The vehicle may include first and second steering control loops that determine the vehicle's position and heading errors, respectively. Separate commands are generated from these control loops to steer the vehicle in a manner that tends to reduce these errors. The vehicle may include a forward and a rearward pair of wheels. For cor...

A magnetic heading sensor alignment device for an acoustic towed line array s described. It includes a generally cylindrical non-magnetic piece having a longitudinal opening along its central axis to accommodate the heading sensor. A plurality of longitudinal non-magnetic strips or springs are provided around the cylindrical piece by securing them at the ends of the cylindrical piece to form a cage. This provides a spring-like action when the alignment device including the heading sensor is inse...

A system of movable headings for bookkeeping includes a cardboard heading strip slidable into transparent plastic envelopes, and the envelopes which are glued to pages of record books. Headings need be written on the heading strip only once. The heading strip then can be moved to another book, or to the next sheet in the same book, for reuse. In a sheaf of pages, the envelope can be moved from a top page to the next page and the page area occupied by the envelope on the previous page removed. A ...

A method of controlling an electronic compass assembly includes calibrating magnetic field sensors to produce a calibration product and determining whether a magnetic interference condition exists based upon the calibration product. In one example, the calibration product includes a calibration ellipse. In another example, the method includes determining a first length of time that corresponds to a duration of a magnetic interference condition or a second length of time that corresponds to an el...

A method and apparatus for heating a charging unit to an appropriate temperature in a uniform manner is provided. In accordance with one example embodiment of the present invention, a heater for use in a charger includes a base. First and second contacts are disposed on the base. A heating element couples the first contact and the second contact. The heating element has an energy density that increases approximately exponentially from a first energy density at locations distal from the first and...

Generally, the present invention relates to an improved headguard to be worn by soccer players that protects the forehead during the act of heading the soccer ball without compromising the integrity of the game. In its preferred embodiment, the protection device cushions the forehead through a combination of soft padding and a custom molded plastic insert. Preferably, the custom molded rigid polymeric insert is sandwiched between two layers of padded, elastic fabric in the form of a headband sur...

When the location of a vehicle is detected based on the outputs of distance and heading sensors, an absolute heading of the vehicle is corrected with a difference between a movement direction of the vehicle obtained during the time that two external location data are obtained by a GPS receiver and an estimated movement direction of the vehicle calculated based on the estimate vehicle location outputted from an estimated location detecting unit.

A combined heading and depth sensor for acquisition of both compass heading and depth data and transmission of the combined data over a two wire communication link as a single packet of information to a remote data acquisition unit. The sensor includes a remote reading compass assembly, a depth sensor and circuitry to interface the compass and depth sensors to the communication link. A communication protocol is defined permitting addressable interrogation of a plurality of combined heading and d...

A circular heading machine for excavating tunnels by advancing a machine in stepwise fashion and erecting tunnel supports, having an elongate machine body at the forward end on which a forwardly directed cutter boom is mounted. Rams advance the machine body in stepwise fashion acting against grippers and a profile ring limits peripheral movement of the cutter boom to form an accurate profile. A gathering apron is provided at the forward extremity of the machine body. The cutter boom is mounted o...

This invention employs a magnetometer as a magnetic heading reference for a vehicle such as a small aircraft. The magnetometer is mounted on a directional dial in the aircraft in the vicinity of the pilot such that it is free to turn with the dial about the yaw axis of the aircraft. The invention includes a circuit for generating a signal proportional to the northerly turning error produced in the magnetometer due to the vertical component of the earth's magnetic field. This generated signal is ...